Adele named her sophomore album "21" after her age at the time she was recording it. This week, the title takes on new significance, as "21" becomes the 21st album in the history of Nielsen SoundScan to sell 10 million copies.

Last week the set -- which hasn't left the Billboard 200 since its debut at No. 1 in February 2011 -- sold 28,000 copies, bringing its total to a whopping 10,020,000. And that's before holiday shopping ramps up.

In a detailed analysis, Billboard's Keith Caulfield notes that "21" is one of eight albums to move 10 million copies in their first two years of release. The others include Santana's "Supernatural," the "Bodyguard" soundtrack and "Jagged Little Pill" by Alanis Morissette. N Sync's "No Strings Attached" and the Backstreet Boys' "Millennium" got there even faster, hitting the 10-million mark in less than 11 months.

Early congratulations to the English singer appeared Tuesday in the form of tweets from Jermaine Dupri and OneRepublic, whose Ryan Tedder co-wrote and produced "21's" final single, "Rumour Has It." "Insane in the membrane!" the band wrote.

Two other discs have been certified this year for sales of 10 million (Linkin Park's "Hybrid Theory" and Usher's "Confessions") while at least one more seems likely before New Year's Eve. "Ten," the 1991 debut by Pearl Jam, is currently at 9.98 million sold.